ball screw is a mechanical linear actuator that translates rotational motion to linear motion with little friction. A threaded shaft provides a helical raceway for ball bearings which act as a precision screw. As well as being able to apply or withstand high thrust loads, they can do so with minimum internal friction.

They are made to close tolerances and are therefore suitable for use in situations in which high precision is necessary. The ball assembly acts as the nut while the threaded shaft is the screw.

Features of Ballscrews

High ReliabilityHigh AccuracyLong DurabilityHigh Working EfficiencyNo Backlash and with High Rigidity

PMI Ballscrews are made of German Alloy steels, which are well quenching and tempering treated for good rigidity, along with suitable surface hardening to ensure long durability.

Balls are rotating inside the Ballscrew nut to offer high working efficiency. Comparing with the traditional ACME screws, which work by friction sliding between the nut and screw, the Ballscrews need only 1/3 of driving torque. It is easy to transmit linear motion into rotation motion.

Construction of a Ballscrew

The circulating balls travel inside the thread form of the screw and nut, and balls are recirculated through various types of return mechanisms. If the ball nut did not have a return mechanism the balls would fall out of the end of the ball nut when they reached the end of the nut. For this reason, several different recirculation methods have been developed.

How to use Ballscrew

A motor is use on one end of the Screw to provide it with the circular motion, as the screw rotates it gives the straight motion to the nut, thus actuating it in a linear motion.

The table on the top is mounted to the Ballscrew to carry the workpiece from one point to another.


Classification of Ballscrews

Majorly Ballscrews are divided into 2 categories i.e., Ground Ballscrews and Rolled Ballscrews depending on the lead accuracy.

Below you can see the basic difference between Rolled and Ground Ballscrews:

 Rolled BallscrewGround Ballscrew
Lead Accuracy50 Microns (C10)3.5 – 18 Microns (C0 – C5)
CertificateNot ProvidedProvided
Axial Play100 Micron (0.1mm)Zero Backlash
AssemblyNut and Screw provided separateNut and Screw are provided in assembly
CustomisableMostly used in Standard specificationsCan be made according to Customer Drawings
Nut ShapesMany different shapes of Nut are available as per customer applicationDifferent shapes of Nut can me made according to customer dimensions
Manufacturing ProcessThread RollingGrinding

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